Rainwater Harvest Calculator
South West Tech — how much water your roof can catch
— litres / year
| Every 1 mm of rain gives you | — |
| Average per week | — |
| A 25 mm storm fills | — |
Rainfall figures are Bureau of Meteorology long-term averages — actual years vary a lot out here, so size storage for the dry ones. Rule of thumb: 1 mm of rain on 1 m² of roof = 1 litre. South West Tech — 0488 224 284.